Bearing and steel therefor



Patented May 26, 1953 BEARING AND STEEL THEREFOR Kan F. "Scha'uwe'cker,Franklin Park, 111., assign-or to United States Steel Corporation, acamera.-

tion of NewJersey No Drawing. Continuation of application Serial N0.109,803, August. 11, 194,9. 31111502121611 A'I lnfil 30, 1951,Serial'No. 223,830

2 Glaims.

This invention relates to improvements in; bearings and steels therefor.The service'life of bearings, such as ball and roller bearings, is inmany installations .toa large degree dependent on the resistance thereofto softening under the high temperatures to which they are subjected.Moreover in forming bearings, it is necessary that" the steel have ahigh degree of forg'eabili'ty.

It is accordingly an object of the present invention to providesteel'bearings which have an increased service life despite their beingsubjected to high temperatures.

It is a further object to provide steels for bearings which arerelatively stable at high temperatures and which have a high degree'ofresistance to softening at elevated temperatures.

' t is another object to provide steels for bearings-which will regainto a large degree any hardnessloss due to being subjected to unduly hightemperatures in service.

It is a iurtheraobject toprovide such qualities in a steel-which ishighly forgeable.

I have, discovered that the foregoing objects can be attained byalloying between .75 and 1.25% aluminum and. .20 and 55%. silicon, withthe aluminum plus silicon content being between'.-1.00 and 1.75%, withhardenable bearing steel. While this is beneficial tohypereutectoid'bearing steels generally, it is particularly trueofhypereutectoid bearing steels having a room temperature Rockwell Chardness or at least '60 after quenching. Preferably the bearing steelsof this invention will contain between .39 5 and 1.15% carbon, .25 to6G% manganese, .20 to 50% silicon, ..35% maximum nickel, 1.35 to 1.65%chromium, .35 maximum copper with the balanceiron except for residualelements incommonamounts.

{The hereinafter presented data obtained. from the heats of steels shownin Table I produced Icy-conventional practice in a high-frequency induction furnace are believed't'o clearly-illustrate ability of myimproved steel to harden and retain its hardness despite :beingsubjected to high temperatures. 1

TABLE I Heat No. Mn Si Ni or Mo- A1 1 1.02 .59 .50 1.50 None 2. 1. 09.62 .59 1. 58 1.18 3 1.02 .35 .29 21 1. 51 .24 None 1 1.10 .41 .30 1. 441.12 5 64 96 20 24 None fi 63 .99 .41 .25 1. 05 7 .51 .75 .21 1. 75 .99.25 None 10 8 .52 .80 .23 1. 65 .80 .26 1.06

;-The hardness of certain of the foregoing steels was determined afterheating for 20 minutes at the temperatures :set forth in Table II. Thespecimens used were about 1 inch in cross section and the hardnessmeasured with a diamond penetrator. For the sake of convenience ofcomparison, the values obtained were converted to Rockwell C readings,using conversion figures recommended by the-American society forTes'tmg- Materials 132-48437).

TA LE Testing to- 3N0 Al 4-AI 7N0 Al Room (before test) 200 J5 0 F Room(after test) An examination 'of this table shows that the decrease orhardness of specimens heated to elevated temperatures is much slower forthe steel containing 1% :aluminum and theqrec'overy after return to roomtemperature much greater.- it. is also noted that these qualities aremuch more pronounced in the hypereutectoid steel containing aluminum andlow -nickel.

The resistance to softening of the steels of my invention upon holdingat elevated temperatures for prolonged periods of time is illustrated inthe following Table III. This table gives the room temperature hardnessvalues in Rockwell C figures obtained after heating, for thetemperatures and times indicated, specimens quenched in water from abovethe An point and.

TABLE III 1--No A1 2-A1 5-No Al 5Al 8-Al As quenched 65. 66. 0 64. 02. 064. 0 Drawn at 350 F. for:

2 Hours i 60. 3 62. 2 58. 0 57. 5 55. 0 4 Hours 60. 6 62. 8 56. 0 55. 054. 5 28 Hours 60. 8 62. 8 58.0 58.0 52.0 Drawn at 450 F. for:

60. 4 62. 3 54. 0 58. O 55. 0 60. 6 62. 8 52. 0 58. O 56. 0 28 Hours 58.2 62. 8 55. 5 55. 0 53. 0 Drawn at 550 F. for:

2 Hours 59. 4 62. 1 55.0 56.0 53.0 4 Hours 59. 4 62. 2 54. 0 57. 0 54. 028 Hours 59. 2 62. 1 52. 0 56. 6 51. 0

The figures of the foregoing Table III show the influence of 1% aluminumin resistance to softening after various periods at varioustemperatures. The difference is again much more pronounced in thehypereutectoid steels.

It is clear from the tables thatalloying hardenable steels with about 1%of aluminum ranof heating. This permits operation of bearing madetherefrom at high temperatures, and greatly reduces the dangerscaused bysoften-.

, Moreover, after drawing at 550 F. for 28 hours,

.20. ders them more resistant tothesoftening effect .cient1y hard asquenched.

the steel containing less than 1% aluminum plus silicon did not-retainhardness for satisfactory service at such temperature, falling below 60R The steel with over 1.75% aluminum plus silicon retained its hardness,but was not suffi- It should be noted ing of steel induced by temporaryoverheating. that the 1 2% aluminum plus silicon not only In the case ofheat No. 4, for example, no damdeveloped satisfactory hardness but alsoretained age for bearings composed of such steel can be its hardnesssatisfactorily for bearing service. expected after overheating for 20minutes at The following Table VI indicates the results 600 F., whilethe same overheating would seriof upset forging tests made on specimens/2" ously-affect bearings of the same composition 30 diameter x 1"specimens of the above strips without aluminum. which were reduced to/8" and A" thickness.

' TABLE VI Forgeability Upset I Forging Tempe ature, F. Heat No. gfi figf fi die. x 1" 1,850 1,950 2,050 2,150

9 )4; surface 0 I Surface Surface 0. Surface 0. K.

do. 110.... .do Do. 10 H 34 .do ...do. Do. .do.. do D0. 11 Unforgeable.Ruptured... upt Surface Rough.

Ruptured. Surface 0. Surface Rough. Ruptured.

, Such beneficial qualities, however, are only This clearly shows that atotal aluminum plus obtainable when the aluminum plus the siliconsilicon of over 1.75% results in the steel not content is maintained inthe range of 1.00 to nly having p00 h de abi ty but also are not 1.75%.To further illustrate this, the following satisfactory for hot workingby commercial mill heats of steel were made and tested as follows: p ace This is a continuation of my copending ap- TABLE plication Serial No.109,803, filed August 11, 1949, j; now abandoned. HGBFNQ C or A1 While Ihave shown and described several I I specific embodiments of myinvention, it will be 9 'fgg fgg fiy "?3; "f2 understood that theseembodiments are merely 10 1.18 for the purpose of illustration anddescription and that various other forms may be devised Specimens ofthese heats of 1%." diameter rgg igggg zg fi g m mventlon' as definedturned to 1" diameter by 3" in length were I claim hed f om normalized1600 F and water quenc r l. A bearing steel characterized by goodforgeabout 1475 The room temperature Rock' ability and by highhardenability and retention wen C hardnesos m q g of hardness afterquenching from above its A61 drawing at 550 for 8 ours gwen m 8 pointand thereafter subjected to prolonged following Table 65 heating at 550R, said steel containing from TABLE v about .95 to 1.15% carbon, .25 to.60% manganese, 35% maximum nickel, 1.35 to 1.65% Drawn 550 F, chromium,.35% maximum copper .75 to 1.25% h I I Dfl AsQuenc ed M2811 l Hencealuminum and .20 to 50% silicon, the total of aluminum plus siliconbeing between about 1.00 2 2, g g-g and 1.75%, the balance being ironand residual iiIIIIIIIIIIIIIIII H.614 11.5814 310 amounts of otherelements.

2. A bearing steel characterized by good forgeability and by a hardnessin excess of 60 Re after water quenching from about 1475" F. re-

tention of room temperature hardness in excess of 60 Re after prolongedheating at 550 F., said steel containing from about .95 to 1.15% carbon, .25 to .60% manganese, 35% maximum nickel, 1.35 to 1.65% chromium,35% maximum copper, .75 to 1.25% aluminum and .20 to 50% silicon, thetotal of aluminum plus silicon being between about 1.00 and 1.75, thebalance iron and residual amounts of other elements.

KARL F. SCI-IAUWECKER.

References Cited in the file of this patent Number FOREIGN PATENTS

1. A BEARING STEEL CHARACTERIZED BY GOOD FORGEABILITY AND BY HUGHHARDENABILITY AND RETENTION OF HARDNESS AFTER QUENCHING FROM ABOVE ITSA-E1 POIINT AND THEREAFTER SUBJECTED TO PROLONGED HEATING AT
 550. F.,SAID STEEL CONTAINING FROM ABOUT .95 TO 1.15% CARBON, .25 TO .60%MANGANESE, .35% MAXIMUM NICKEL, 1.35 TO 1.65% CHROMIUM, .35% MAXIMUMCOPPPER, .75 TO 1.25% AALUUMINUM PLUS SILICON, THE TOTAL OF ALUMINUUMPLUS SILICON BEING BETWEEN ABOUT 1.00 AND 1.75%, THE BALANCE BEING IRONAND RESIDUAL. AMOUNTS OF OTHER ELEMENTS.